Apparatus for the manufacture of pressed tablets



Oct. 20, 1970 A. ROBERTS 3,534,440

APPARATUS FOR THE MANUFACTURE OF PRESSED TABLETS Filed March 29, 1968 //VVENTOR ALBERT 'ROYJERTS ATTORNEYS United States Patent Office 3,534,440 Patented Oct. 20, 1970 3,534,440 APPARATUS FOR THE MANUFACTURE OF PRESSED TABLETS Albert Roberts, Salford, England, assignor t Colgate- Palmolive Company, New York, N.Y. Filed Mar. 29, 1968, Ser. No. 717,098 Claims priority, application Great Britain, Aug. 18, 1967, 38,246/ 67 Int. Cl. C11d 13/14; B41b 11/62 US. CI. 1816 Claims ABSTRACT OF THE DISCLOSURE Bodies of soap, detergent and the like are pressed to final shape and/ or size and at the same time formed with indented or raised surface indicia in a die press wherein the lower die has a cavity wherein the body is placed and the upper die has a pressing face for engaging the body. A detachable and replaceable section of embossed tape bearing the indicia to be formed in the body as it is pressed by the dies is mounted on either the upper die pressing face or the bottom of the cavity, or on both where opposite sides of the body are to be formed with indicia.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to the manufacture of bodies of materials formable by pressing, more particularly but not exclusively soap and synthetic detergent bars, tablets and the like. As used herein the term body includes cakes, bars, tablets and other solid shapes which are brought to their final shape and/or size by pressing between dies, and also bodies formed when a quantity of powdered or fluid material is placed in a die cavity and pressed to solid shape retaining condition.

It is often desired to impress such bodies with characters such as a trademark or advertising matter, which is usually done by providing one or more of the pressing dies with the appropriate reverse indicia, raised where the indicia are to be impressed into the body or indented where the indicia on the body are to be raised. Such dies are expensive, and their cost is considerably increased where the indicia have to be provided as by direct engraving or molding permanent formations thereon. Permanent indicia restricts the dies to one usage run. This may be relatively unimportant where very long runs are required, as where a single indicia is desired, but the cost of making separate dies bearing different permanent indicia is apt to be prohibitive for short runs, as for example in the manufacture of soap bars for different hotels or motels. It is known to make dies with replaceable inserts, but these are usually expensive in that special insert forming or attachment techniques and arrangements are required.

The present invention provides a surprisingly non-obvious solution to this problem simply and with little expenditure of either time or money.

According to a preferred embodiment of the invention a piece of thin embossable material is embossed with the desired indicia and attached, as by pressure sensitive adhesive means, to one or more pressing faces of a pair of dies between which the body is to be pressed. One of the dies, preferably the lower, is usually formed with a cavity to receive a mass of material to be pressed so that opposed pressing faces are provided on the lower side of the upper die and the bottom of the cavity. An indicia piece may be mounted on either face or on each of them. These are primary objects of the invention.

The thin material is conveniently embossable palstic or metal strip or tape having an adhesive backing, such as is widely used for labelling and the like. Such tapes are described for instance in British Pats. Nos. 866,024, 948,765 and 956,304. For making labels and the like such tape may be embossed by means of letter or other character dies, which force up corresponding shapes out of the plane of the tape, the material being thereby distorted beyond its elastic limit so that the shapes of he characters remain permanently raised. For impressing asymmetrical characters such as letters and words, the characters embossed in the tape must be reverse or mirror images of the indicia to be impressed into the body.

It has been found, surprisingly, that despite the relatively high pressures used in pressing soap, detergent and the like, the raised characters on the tape are not noticeably pressed down or otherwise distored during the pressing operation and long runs of bodies can be pressed without appreciable deterioration of the quality of the impressed indicia.

It has also been found, surprisingly, that provided the pressing surface is clean when the tape is applied, there is no tendency for adhesion to break down, even at the edges, in the course of long runs, yet the tape can easily be peeled off when it is to be replaced.

In one embodiment of the invention a shallow recess is formed in the pressing face of the die of a depth substantially equal to the thickness of the embossed material, and the piece of material is shaped to fit into the recess. In this case there will be no appreciable impression in the pressed body corresponding to the base portion of the embossed material.

Since the plain or shallowly recessed dies which are used in performing the invention are considerably cheaper than dies with integrally formed permanent indicia or with presently conventional removable inserts, and since the cost of the embossed strip material is very low, so that used strips may be disposable, the present invention make even very short runs economically feasible.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an exploded view in section showing upper and lower pressing dies formed and associated according to a preferred embodiment of the invention;

FIG. 2 is a bottom plan view of the upper die taken substantially on line 22 of FIG. 1;

FIG. 3 is a top plan view of the lower die taken substantially on line 33 of FIG. 1;

FIG. 4 is a top plan view showing the pressed indicia bearing bar or tablet when removed from the dies;

FIG. 5 is a section substantially on line 55 of FIG. 4;

FIG. 6 is a section showing an embossed tape structure;

FIG. 7 is an enlarged section showing attachment of the embossed tape to the die pressing surface;

FIG. 8 is a fragmentary elevation mainly in section illustrating a further embodiment of upper die structure; and

FIG. 9 is an exploded view like FIG. 1 but showing the indicia tape adhesively attached to the pressing face at the bottom of the die cavity.

PREFERRED EMBODIMENTS OF INVENTION FIG. 1 illustrates an upper metal die 11 and a lower metal die 12 suitably conventionally mounted for movement toward each other to compress a body 13 of soap, detergent or the like placed in an upwardly open cavity 14 at the planar top surface 15 of lower die 12. Upper die 11 has a planar bottom surface 16 serving as a material pressing face adapted to engage the lower die 12 at top face 15 when the dies are brought together. The body 13 is of such size as to project slightly above face 15 and so it will be compressed to a final shape and size 3 dictated by the cavity dimensions when the dies are brought together. Cavity 14 has a bottom planar face which in the die action serves as a pressing face opposed to the pressing face at 16.

Mechanism for mounting the dies and bringing them together under sufficient positive pressure to compress body 13 may be conventional, such as may be used in any die press assembly and such forms no part of the present invention. Further, while only one die cavity 14 is shown for illustrating the invention, any number of separate similar cavities may be provided in a single lower die for multiple operation.

The invention comprises providing an indicia forming means 17 on the portion of pressing face 16 above cavity 14 which is sturdy enough for a large number of pressing operations without damage or deformation so as to reproduce the same indicia on each body being pressed, but which is readily removable and replaceable by another indicia forming means representing a different indicia.

It has been discovered that this indicia forming means may be a strip of thin suitably rigid tape embossed to project the required indicia design from one surface and provided on its opposite surface with a layer of pressure sensitive adhesive. The tape strip is embossed by passing it through a suitable tape embossing device such as shown in US. Pat. No. 3,047,443. Tape strip 17 comprises essentially a base strip 18 of suitable deformable but rigid material capable of being embossed and retaining the embossed shape. When the tape is embossed the indicia characters 19 project cleanly above a fiat surface of the tape. A suitable layer 21 of pressure sensitive adhesive is spread over the opposite surface of tape 18 and layer 21 is covered by the usual removable tear sheet 22 protecting the adhesive but removable when the tape is to be applied to the die. FIGS. 6 and 7 show these components in exaggerated thickness size for clarity of dis closure. Usually the tape is provided in laminated form and embossed to the shape shown in FIG. 6.

Advantageously base 18 may be a strip of polyvinyl chloride or equivalent relatively rigid plastic sheeting which undergoes cold flow when embossed and retains the imparted shape. Base 18 may have a sheet thickness in the neighborhood of 50 to 100 thousandths of an inch, and the embossed characters 19 usually stand about that distance from the tape surface.

Other base materials such as laminated plastic and fabric and malleable metals such as aluminum or copper of suitable thickness (about four to seven millimeters) may be used, and in general embossed tapes preferably usable in the invention are well illustrated by the tapes disclosed in the above-identified British patents.

The protective sheet 22 is removed and strip 18 is pressed onto upper die face 16, [with the characters 19 centered with the cavit below, until the strip is firmly adhesively attached to the face as shown in FIG. 7.

In practicing the invention the upper and lower dies, with a body 13 of material to be compressed in cavity 14 and a suitable indicia bearing strip 17 on face 16, are brought together under positive pressure until die surfaces and 16 abut. Body 13 is thereby shaped to final form and at the same time its upper surface engaged by tape strip 17 is formed with indented indicia corresponding to the projecting characters 19 on the embossed strip. FIGS. 4 and 5 show the body 13 in final form with indented indicia 23 in the top surface.

Although the tape 17 is of very small thickness, as above described, it usually also impresses into the top surface of body 13 a very shallow recess corresponding in shape and area to the section of tape adhering to face 16. While such a recess does not interfere with the pro duction of visible indicia 23, and even for some purposes frames and enhances the visibility of such, it may be eliminated by the embodiment of the invention shown in FIG. 8 wherein the embossed strip 17 is adhesively attached to the bottom of a suitably shaped shallow recess 24 in upper die face 16, the depth of recess 24 being equal approximately to tape thickness.

As will be apparent from FIG. 8, in such an arrangement the downwardly facing tape surface is flush with die face 16 and only the characters 19 project below die face 16 and so only those characters are indented into the top surface of compressed body 13.

The foregoing arrangement may be used for compressing desired relatively short runs of for example several thousand soap bars for a certain hotel, with remarkable fidelity in reproduction of indicia '23, and then a new tape 17 substituted for a different run. While tape 17 seems relatively fragile it does not rupture or deform under the high soap forming pressures, and it is believed that the air trapped in spaces 25 opposite the embossed characters 19 cooperates with inherent resiliency of the strip material to effectively uniformly cushion the strip to prevent destructive localized stress regions. In any event the results are unexpectedly good. When a new run of different indicia is desired, the only changeover operation necessary is to peel off strip 17 and replace it with a new strip bearing the desired indicia.

There is no storage problem since the used strips 17 are disposable and new embossed strips easily and quickly made. The invention provides maximum flexibility for changing designs and words to newer and up-to-date forms and arrangements simply by making new embossed strips.

While the formation of indented indicia from projections on embossed tape is above described and illustrated, it will be clear that the invention is equally applicable to the use of the reverse side of an embossed tape to form raised characters on the soap or other body being pressed to final form. Also the invention contemplates the formation of both indented and raised indicia portions using a single formed tap bearing both types of indicia forming regions.

FIG. 9 illustrates a further embodiment of the invenvention wherein the indicia bearing strip 17 may be at tached to pressing face 10 at the bottom of cavity 14, and the upper die pressing face may be planar and smooth. The indicia forming action is essentially the same as a soap, detergent or like body is compressed between the dies. Pressing face 10 may be recessed similarly to face 16 as shown in FIG. 8. If indicia is to be impressed on both the upper and lower sides of the body 13, suitable indicia bearing strips may be attached to both pressing faces 10 and 16.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. Apparatus for pressing a body of material to a defined solid shape and at the same time forming indicia on a body surface comprising cooperating dies adapted to be brought together under pressure and provided with opposed pressing faces at least one of which is formed within a die cavity for receiving a body of said material and indicia forming means is provided on at least one of said pressing faces; characterized by said indicia forming means being a strip of tape removably attached to its die pressing face by a pressure sensitive adhesive layer and having indicia forming regions in forming engagement with said body surface when the dies are brought together.

2. The apparatus defined in claim 1, wherein said indicia forming means is a strip of thin embossed tape.

3. The apparatus defined in claim 1, wherein said formed strip is attached to the pressing face of one die disposed opposite a cavity in the other die.

4. The apparatus defined in claim 1, wherein said formed strip is attached to the pressing face at the bottom of a die cavity.

5. The apparatus defined in claim 1, wherein said formed strip is seated in a shallow recess in a die pressing face, said recess having a depth equal substantially to tape thickness.

6. The apparatus defined in claim 1, wherein said indicia forming means is a strip having a base of relatively rigid emhossable plastic having the required indicia permanently formed therein.

7. The apparatus defined in claim 6, wherein said plastic is a polyvinylchloride material.

8. The apparatus defined in claim 1, wherein said indicia forming means is a strip having a base of malleable metal with the required indicia permanently formed therein.

9. The apparatus defined in claim 1, wherein said indicia forming means is a short strip of embossed tape material having a thickness of only up to about to thousandths of an inch.

References Cited I. SPENCER OVERHOLSER, Primary Examiner JOHN E. ROETHEL, Assistant Examiner US. Cl. X.R. 

